What are M12 circular connectors?

M12 connectors are a metric circular connector product used in industrial automation and other harsh environment applications where compact, rugged, and reliable power, signal, and data connections are needed. One of the most commonly specified connectors in the industrial market, the M12 is considered the backbone of IIoT system connectivity.

The metric-screw-sized M12 connector is part of a family of electrical connectors (M5 through M12 types) identified by the diameter of its outer threads. M12s are standardized to IEC-61076-2-101. They are a highly versatile product type, and manufacturers offer a wide range of locking mechanisms and other options. Per the standard, this connector is interchangeable and backwards compatible with other M12 interfaces with the same coding, including interoperability among manufacturers. They handle bandwidth needs up to 10 Gb/s, power to 16 V, and may be configured to support Profinet, SPE, and fieldbus protocols.

German connector company Lumberg introduced the M8/M12 connector interface at Hannover Fair in 1985. It was initially devised as a waterproof alternative for the older RK30 sensor connector, a common choice for automotive manufacturing facilities at the time. The M12 is now available from many manufacturers and this powerful, versatile interconnect is widely used in factory automation, autonomous robots, data transmission, and controls.

Design Notes

• Standards M12 connectors are the IEC 61076-2-101:2012 standard. The original IEC standard was published in 2003 and is currently in its third revision. In 2021, a new push-pull M12 standard, known as IEC 61076-2-010;2021, was released.
• Coding In order to prevent mis-mating, M-family circular connectors are available in specific coding options that define pin counts and arrangements. M12s are available in A (3-17 poles), B (2, 4, or 5 poles; mainly used on Profibus and Interbus applications), C (3 to 6 poles; includes a dual keyway to prevent mismating), D (4-poles; standard on Ethernet, ProfiNet, and EtherCat field devices and industrial CAT5e cables), K (5 poles [4+PE]; rated up to 630VAC/DC), L (4 poles or 5 poles [4+PE] with a current rating of up to 16A per pole and a maximum voltage rating of 63VAC/DC), S (3-pole [2+PE] or 4-pole [3+PE]), T (designed for DC power connections; rated up to 63VDC/AC, 4 poles with each pole rated to 12A), X (8 poles, up to 10 Gb/s), and Y (power and data in a single cable; 8 poles split into two groups of 4 that are galvanically separated with a metal coding that looks like a Y).
• Cable Considerations M12 connectors are commonly used with Cat5e and Cat6A cable types.
• Current Rating Up to 16V
• Mounting Options M12s are available in mounting options including through-hole, surface mount, and wave soldering.Materials Metals used for M12 shells include stainless steel, brass, copper, gold, and alloys.
• Ruggedization M12 connectors and their cable assemblies are designed to ensure rugged performance in high-reliability and harsh environment applications, including those that feature temperature extremes, radiation, rough handling, chemicals, and other environmental factors.
• Sealing M12 connectors are available in IP67, IP68, and IP69 versions. Environmental protection against fluid and particulate ingress is part of what makes this connector a mainstay in rugged operational environments. Waterproofing and sealing are especially important in fluidic and pneumatic configurations.
• Interference Electromagnetic interference (EMI) or radio-frequency interference (RFI) is a significant concern for devices used in environments filled with electronic equipment. Shielded and unshielded connector and cable assembly options are available.
• Handling Advantages M12 connectors are designed to provide fast and easy connections even in challenging conditions. They are available in screw-type, bayonet, and ergonomic push-pull locking mechanism for blind mating situations. Keying, color coding, and LED options are available to increase mating reassurance. This is considered a field serviceable connector and it is backwards compatible.

Markets, Sectors, and Applications:

Industrial (factory automation and control systems, I/O modules, sensors, actuators, motors, Industry 4.0 and IIoT applications, renewable energy), Automotive (manufacturing), Transportation (heavy equipment, agricultural equipment); machine tools